Re: [PATCH 5.15 00/23] 5.15.160-rc1 review

[Chuck Lever]

On Thu, May 30, 2024 at 01:11:47PM +0100, Jon Hunter wrote:
> 
> On 29/05/2024 21:59, NeilBrown wrote:
> 
> ...
> 
> > Thanks for testing.
> > I can only guess that you had an active NFSv4.1 mount and that the
> > callback thread was causing problems.  Please try this.  I also changed
> > to use freezable_schedule* which seems like a better interface to do the
> > same thing.
> > 
> > If this doesn't fix it, we'll probably need to ask someone who remembers
> > the old freezer code.
> > 
> > Thanks,
> > NeilBrown
> > 
> >  From 518f0c1150f988b3fe8e5e0d053a25c3aa6c7d44 Mon Sep 17 00:00:00 2001
> > From: NeilBrown <neilb@xxxxxxx>
> > Date: Wed, 29 May 2024 09:38:22 +1000
> > Subject: [PATCH] sunrpc: exclude from freezer when waiting for requests:
> > 
> > Prior to v6.1, the freezer will only wake a kernel thread from an
> > uninterruptible sleep.  Since we changed svc_get_next_xprt() to use and
> > IDLE sleep the freezer cannot wake it.  we need to tell the freezer to
> > ignore it instead.
> > 
> > To make this work with only upstream requests we would need
> >    Commit f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
> > which allows non-interruptible sleeps to be woken by the freezer.
> > 
> > Fixes: 9b8a8e5e8129 ("nfsd: don't allow nfsd threads to be signalled.")
> > Signed-off-by: NeilBrown <neilb@xxxxxxx>
> > ---
> >   fs/nfs/callback.c     | 2 +-
> >   fs/nfsd/nfs4proc.c    | 3 ++-
> >   net/sunrpc/svc_xprt.c | 4 ++--
> >   3 files changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
> > index 46a0a2d6962e..8fe143cad4a2 100644
> > --- a/fs/nfs/callback.c
> > +++ b/fs/nfs/callback.c
> > @@ -124,7 +124,7 @@ nfs41_callback_svc(void *vrqstp)
> >   		} else {
> >   			spin_unlock_bh(&serv->sv_cb_lock);
> >   			if (!kthread_should_stop())
> > -				schedule();
> > +				freezable_schedule();
> >   			finish_wait(&serv->sv_cb_waitq, &wq);
> >   		}
> >   	}
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index 6779291efca9..e0ff2212866a 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -38,6 +38,7 @@
> >   #include <linux/slab.h>
> >   #include <linux/kthread.h>
> >   #include <linux/namei.h>
> > +#include <linux/freezer.h>
> >   #include <linux/sunrpc/addr.h>
> >   #include <linux/nfs_ssc.h>
> > @@ -1322,7 +1323,7 @@ static __be32 nfsd4_ssc_setup_dul(struct nfsd_net *nn, char *ipaddr,
> >   			/* allow 20secs for mount/unmount for now - revisit */
> >   			if (kthread_should_stop() ||
> > -					(schedule_timeout(20*HZ) == 0)) {
> > +					(freezable_schedule_timeout(20*HZ) == 0)) {
> >   				finish_wait(&nn->nfsd_ssc_waitq, &wait);
> >   				kfree(work);
> >   				return nfserr_eagain;
> > diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> > index b19592673eef..3cf53e3140a5 100644
> > --- a/net/sunrpc/svc_xprt.c
> > +++ b/net/sunrpc/svc_xprt.c
> > @@ -705,7 +705,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
> >   			set_current_state(TASK_RUNNING);
> >   			return -EINTR;
> >   		}
> > -		schedule_timeout(msecs_to_jiffies(500));
> > +		freezable_schedule_timeout(msecs_to_jiffies(500));
> >   	}
> >   	rqstp->rq_page_end = &rqstp->rq_pages[pages];
> >   	rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */
> > @@ -765,7 +765,7 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
> >   	smp_mb__after_atomic();
> >   	if (likely(rqst_should_sleep(rqstp)))
> > -		time_left = schedule_timeout(timeout);
> > +		time_left = freezable_schedule_timeout(timeout);
> >   	else
> >   		__set_current_state(TASK_RUNNING);
> 
> 
> That did the trick! Suspend is now working again on top of v5.15.160-rc1
> with this change.
> 
> Feel free to add my ...
> 
> Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>

Since I've heard no objections, I've added this to nfsd-5.15.y for
testing. I plan to send it along to stable@ when testing completes.

-- 
Chuck Lever